DESCRIPTION

The pci set of functions are used for managing PCI devices.
The pci_read_config() function is used to read data from the PCI
configuration space of the device dev, at offset reg, with width
specifying the size of the access.
The pci_write_config() function is used to write the value val to the PCI
configuration space of the device dev, at offset reg, with width
specifying the size of the access.
The pci_enable_busmaster() function enables PCI bus mastering for the
device dev, by setting the PCIM_CMD_BUSMASTEREN bit in the PCIR_COMMAND
register. The pci_disable_busmaster() function clears this bit.
The pci_enable_io() function enables memory or I/O port address decoding
for the device dev, by setting the PCIM_CMD_MEMEN or PCIM_CMD_PORTEN bit
in the PCIR_COMMAND register appropriately. The pci_disable_io()
function clears the appropriate bit. The space argument specifies which
resource is affected; this can be either SYS_RES_MEMORY or SYS_RES_IOPORT
as appropriate.
NOTE: These functions should be used in preference to manually
manipulating the configuration space.
The pci_get_powerstate() function returns the current ACPI power state of
the device dev. If the device does not support power management
capabilities, then the default state of PCI_POWERSTATE_D0 is returned.
The following power states are defined by ACPI:
PCI_POWERSTATE_D0 State in which device is on and running. It is
receiving full power from the system and
delivering full functionality to the user.
PCI_POWERSTATE_D1 Class-specific low-power state in which device
context may or may not be lot. Busses in this
state cannot do anything to the bus, to force
devices to lose context.
PCI_POWERSTATE_D2 Class-specific low-power state in which device
context may or may not be lost. Attains greater
power savings than PCI_POWERSTATE_D1. Busses in
this state can cause devices to lose some
context. Devices must be prepared for the bus to
be in this state or higher.
PCI_POWERSTATE_D3 State in which the device is off and not running.
Device context is lost, and power from the device
can be removed.
PCI_POWERSTATE_UNKNOWN State of the device is unknown.
The pci_set_powerstate() function is used to transition the device dev to
the ACPI power state state. It checks to see if the device is PCI 2.2
compliant. If so, it checks the capabilities pointer to determine which
power states the device supports. If the device does not have power
management capabilities, the default state of PCI_POWERSTATE_D0 is set.
The pci_find_bsf() function looks up the device_t of a PCI device, given
its bus, slot, and func. The slot number actually refers to the number
of the device on the bus, which does not necessarily indicate its
geographic location in terms of a physical slot. Note that in case the
system has multiple PCI domains, the pci_find_bsf() function only
searches the first one. Actually, it is equivalent to:
pci_find_dbsf(0, bus, slot, func);
The pci_find_dbsf() function looks up the device_t of a PCI device, given
its domain, bus, slot, and func. The slot number actually refers to the
number of the device on the bus, which does not necessarily indicate its
geographic location in terms of a physical slot.
The pci_find_device() function looks up the device_t of a PCI device,
given its vendor and device IDs. Note that there can be multiple matches
for this search; this function only returns the first matching device.

IMPLEMENTATIONNOTES

The pci_addr_t type varies according to the size of the PCI bus address
space on the target architecture.

AUTHORS

BUGS

The kernel PCI code has a number of references to â€śslot numbersâ€ť. These
do not refer to the geographic location of PCI devices, but to the device
number assigned by the combination of the PCI IDSEL mechanism and the
platform firmware. This should be taken note of when working with the
kernel PCI code.